HMS Union was the mercantile City of Kingston that the Royal Navy purchased in 1823 for service as a 3-gun schooner.

The British took possession of the schooner and removed her cargo, which consisted of goods plundered some time before from a French vessel.

The schooner carried three heavy guns, was marked on her mast and sails with the number "104", and had been full of men.

The fire lasted for four-and-a-half hours before the sloop apparently was able to escape, at which time the pirates on shore dispersed into the woods.

The British found a schooner of 80 tons (bm) and one gun moored up a narrow creek, apparently being fitted out for a pirate cruize.

[3] On 30 March Lion, Union, and Hyperion were in Las Carnas Bay in the Colorado Reefs when they came upon a third schooner, this of 80 tons (bm), and armed with one large gun on a pivot mount.

When Lion, Union, and two launches from Tamar approached, the crew of the schooner ran her onshore and escaped into the woods.

[b] In March 1825, the frigate HMS Dartmouth, the schooners Lion and Union, and the USS Gallinipper participated in an operation against Cuban pirates.

United States Navy Lieutenant Isaac McKeever led an attack against a schooner at the mouth of the Sagua la Grande.

The pursuit lasted two days before Magico's crew ran her aground at Manatí, Puerto Rico.

On 16 March 1828 Lieutenant Wills sailed Union from Port Royal, Jamaica, bound for Havana.

The subsequent court martial found that Wills had carried too much sail when close to the land, and had failed to order the regular taking of soundings, with the result that she had struck the Porpoise Rocks at the eastern end of Rose Island.